Paddle wheel inerting

ABSTRACT

A rotary apparatus for purging empty bottles with nitrogen gas includes a rotor from which arms of flexible material radiate. Each arm carries a gas supply lead. The arrangement is that advancing bottles engages the heads and thereby drive the rotor. Valve means is provided whereby each head in turn is placed in communication with a purging gas supply when it reaches a first position and the communication is ended when the head reaches the second position. During its course of travel from the first position to the second position, the head communicates with a respective bottle and the bottle is thereby purged.

TECHNICAL FIELD

This invention relates to a method and apparatus for supplying gas. Inparticular, it relates to the supply of a non-oxidising gas, for examplenitrogen, to flush or purge air from containers, particularly bottles,before the containers are charged with a liquid whose quality is liableto be impaired by oxidation. The method and apparatus according to theinvention find particular utility in the bottling of alcoholic andnon-alcoholic beverages.

BACKGROUND OF THE PRIOR ART

Modern bottling practice includes the step of loading bottles on aconveyer and advancing them, sometimes at rates up to 2000 bottles perminute, to a filling station where they are charged with a liquid, say abeverage. It is known that oxidation causes beverages such as beer todeteriorate. It is therefore desirable to minimise the contact betweenthe beer and the oxygen of the atmosphere during bottling of the beer.It is therefore desirable to flush the empty bottles with anon-oxidising gas such as nitrogen so as to reduce the concentration ofoxygen in the gaseous atmosphere they contain. Known proposals forperforming this flushing step involve passing the bottles from theconveyer line to a station at which they can be flushed with nitrogen.The station normally comprises a carousel which receives bottles from afirst line and returns the duly flushed bottles to a second line. Thisprocedure has two disadvantages. First, the requirement for the carouselor other station at which the bottles can be flushed with nitrogen addsappreciably to the total capital cost of the bottling plant. Second, itincreases the duration of the bottling procedure.

There is thus a need for a method and apparatus which may be used toflush the bottles with a suitable gas while they are being conveyedalong a straight line path, and which preferably do not require a largecapital expenditure. It is an aim of the present invention to provide anapparatus and a method that meet this need.

SUMMARY OF THE INVENTION

According to this invention, there is provided apparatus for flushing aline of advancing containers with gas comprising a multiplicity ofspaced apart gas supply heads each engagable with a container and allable to be moved in concert along an endless path; and valve meansoperable to place each head in turn in communication with a main conduitwhen the head reaches a first chosen position along the path and to endsuch communication when the head reaches a second chosen position,whereby in use each container in turn is able to be engaged by arespective head and flushed with gas.

The invention also provides a method of flushing a line of advancingcontainers with gas comprising advancing a multiplicity of spaced apartgas supply heads, each engagable with a container, along an endless pathsuch that each head in turn engages an advancing container and eachadvancing container in the sequence is engaged by a head, and supplyinggas to each head when it is between chosen positions only, suchpositions including those in which it is in engagement with a container,and thereby flushing the containers with gas.

Preferably, the heads are attached to a rotor which is mounted on afixed shaft whereby the advancing containers are able to drive the rotorand cause each head in turn to engage a respective container and eachcontainer in turn to be engaged by a respective head. An alternative isto provide a separate drive for the rotor, in which instances the shaftmay turn with the rotor. However, providing a separate drive adds to thecost of the apparatus according to the invention and problems may arisein synchronising the speed of rotation of the rotor to the speed atwhich the containers advance. By employing the containers themselves todrive the rotor, and appropriately selecting the number and spacing ofthe heads, continuous rotation of the heads by the line of containers ismade possible.

In an embodiment of the apparatus according to the invention in whichthere is a rotor mounted on a fixed shaft, the rotor preferablyco-operates with a complementary stationary member (`the stator`) todefine the valve means. In such an arrangement, one of the stator andthe rotor defines a circumferential chamber in communication with aninlet for the flushing gas, while the other of the stator and the rotordefines a ring of outlet ports, each in communication with a respectivehead, the arrangement being such that rotation of the rotor brings eachoutlet port in turn into communication with the chamber and hence theinlet. The extent of the chamber is preferably such that it overlaps andhence communicates with typically three or four gas ports. This enableseach head in turn to be supplied with nitrogen (or other flushing gas)as it enters into alignment with a container. The contiguous faces ofthe stator and rotor are preferably formed such that there is a narrowgap and hence gas layer therebetween (say no more than one or two`thou`, i.e. in the order of 0.01 to 0.03 mm).

The containers are typically bottles or other members which are eachformed with a neck such that the internal diameter of their mouth ismarkedly less than the internal diameter of their body.

The heads are preferably connected to the rotor by means of flexiblearms. The arms are preferably made of flexible material, for example,plastics. It is possible to provide conduits communicating with theoutlet ports (if in the rotor) through the arms themselves.Alternatively, and more preferably, there are separate conduitsconnecting each head with a respective port in the valve.

Each head preferably takes the form of a cap having a slot in the rearside thereof. It is not necessary and indeed not preferred for there tobe any close match between the shape of the cap and that of the top ofthe bottle. In operation, the bottle engages the inner surface of theforward side of the cap (with respect to the direction of rotation ofthe heads) and thereby acts to push the rotor so as to advance each headcontinuously along the endless path. The rearward slot facilitatesengagement of the cap with the top of the bottle.

BRIEF DESCRIPTION OF THE DRAWINGS

A method and apparatus according to the invention will now be describedby way of example with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram giving a general view from the side of anapparatus according to the invention.

FIG. 2 shows a detail of the apparatus shown in FIG. 1;

FIG. 3 is a sectional view of a gas flushing head;

FIG. 4 is a sectional elevation of valve for use in association with theapparatus shown in FIGS. 1 to 3, and

FIG. 5 is a schematic plan view of the rotary element of the valve shownin FIG. 4.

The drawings are not to scale.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 of the drawings, there is shown part of a conveyer 2which advances a row of bottles 4 to a filling station where the bottlesare charged with a beverage. As shown in FIG. 2 the bottles are retainedin position on the conveyer 2 by retaining means 5. Referring again toFIG. 1, located above the conveyer 2 is a rotary gas purging apparatus6. The apparatus 6 includes a rotor B which is axially mounted on ashaft 10. Arms 12 of flexible material radiate from the rotor 8 likespokes from the hub of a wheel. As shown in FIG. 1, there are sixteenarms 12. Fewer or more arms may be used. In practice, the main factorsdetermining the number of arms required will be the spacing between theindividual bottles and the length of the arms. Generally, the closer thespacing between neighbouring bottles on the conveyer 2 and the longerthe arms 12, the more arms 12 will be required.

The arms 12 each carry a head (not shown in FIG. 1). Each headcommunicates with a source of nitrogen or other purging or flushing gasby means of suitable tubing (not shown in FIG. 1).

The heads are illustrated in FIGS. 2 and 3 of the drawings. TheseFigures show the heads 20 each connected to the rearward side of arespective arm 12 (having regard to the anti-clockwise direction ofrotation of the arms 12). Any suitable connecting means such as rivetsor bolts may be used for this purpose. Each head 20 comprises a cap 22having a gas introduction nozzle 24 in its top. The nozzle 24 receives alength of tubing 26 which extends from the rotor 8 in a manner that willbe described below. Each head 20 has a slot 28 formed in its rearwardside through which in operation the tops of the bottles 4 may pass.

In operation, at the start of a filling operation, the conveyer 2 shownin FIG. 1 is started and the first bottle in the line passes through theslot 28 of the head 20 connected to the arm 12 which is in the 6 o'clockposition (i.e. pointing vertically downwards). The bottle continues toadvance and as it does so, so it turns the assembly of the rotor 8, arms12 and heads 20 in an anti-clockwise direction. Accordingly, the headthat is immediately behind the one engaging the bottle moves through anarcuate path with a horizontal component of velocity less than thevelocity at which the bottles are advanced, with the result that by thetime the next bottle 4 reaches the 6 o'clock position it has caught thenext head 12. Moreover, as the first bottle proceeds towards the fillingstation (not shown) so it continues to push the assembly of rotor 4,arms 12 and heads 20 in an anti-clockwise direction until the arcuatepath followed by the heads 20 causes the respective head 20 to move outof engagement with the leading bottle 4. By this time the next bottlehas reached the 6 o'clock position as described above. Accordingly,continuous rotation of the assembly of rotor 8, arms 12 and heads 20 ismade possible with each head 20 in turn being engaged by the top of abottle 4 and each bottle 4 in turn engaging a respective head 20. Theretaining means 5 resist any tendency for the bottles to be knocked overby their contact with the arms 12 of the gas flushing apparatus 6.

The arrangement whereby gas such as nitrogen is used to flush thebottles is shown in FIGS. 4 and 5 of the accompanying drawings.Referring to FIG. 4, the rotor mounted on the shaft 10 co-operates witha complementary stationary member or stator 30 which is axially andfixedly mounted on the shaft 10. The stator 30 has an inlet port 32 forgas. The inlet port 32 may communicate by means of a conduit (not shownin FIGS. 4 and 5) with a conduit communicating with a source ofnitrogen. The port 32 at its inner end terminates in an arcuate chamber34 which is formed as an arcuate slot in the inner face of the stator30. The rotor 8 has a number of equally spaced circumferentiallydisposed ports 36 formed therethrough. As shown in FIG. 5, the chamber34 has its mid-point in the 6 o'clock position. As the rotor 8 is causedto rotate by the forward motion of the bottles, so each port 36 in turncomes into registry with the centre of the chamber 34. Preferably theextent of the chamber 34 is such that when one port is in the 6 o'clockposition, the chamber 34 overlaps two other ports one on either side ofthe 6 o'clock port. The ports 36 are each connected to a respectiveconduit 26 that provides gas flow to a respective head 20 of theapparatus 6. Accordingly, it can be arranged that the three ports 36overlapped at any one time by the chamber 34 and hence put incommunication with the inlet port 32, and thus the source of nitrogensupply, are the ones that serve the head 20 for the time being in the 6o'clock position and the two neighbouring head on each respective side.

Accordingly, the supply of nitrogen to each head 20 starts before thehead is in precise alignment with the bottle. Similarly, nitrogen willalso be supplied to the head as it passes beyond the 6 o'clock position.There is accordingly a period of travel of the head on either side the 6o'clock position during which nitrogen is supplied to the bottle.Desirably, the flow rate of nitrogen is arranged so that the bottlereceives at least twice and preferably three times its own volume ofnitrogen. The arrangement is also such that once the head has moved awayfrom a bottle that has advanced sufficiently beyond the 6 o'clockposition, the port 36 placing that head in communication with the sourceof nitrogen via the port 32 and the chamber 34 has passed out ofregistry with the chamber 34 so that substantially no nitrogen isreceived by that port. Accordingly, wastage of nitrogen is kept to aminimum.

In order to keep the contiguous faces of the rotor 8 and stator 30 inproximity to one another, the rotor 8 is biased by a compression spring38 into engagement with the stator. A boss 40 may be provided on theshaft 10 to enable the spring pressure to be adjusted manually.

Another feature of the valve arrangement shown in FIGS. 4 and 5 of thedrawings is that a very shallow recess or gap is provided between thecontiguous facing surfaces of the stator 30 and rotor B to provide for agas bearing therebetween. There will accordingly be some leakage of gasinto those ports 36 not for the time being in registry with the chamber34, but such gas loss will be minimal in comparison with that which issupplied to the bottles.

I claim:
 1. Apparatus for flushing a line of advancing containers withgas comprising a multiplicity of spaced-apart gas supply heads in avertical plane each engagable with a container and all able to be movedin concert along an endless path; and valve means operable to place eachhead in turn in communication with a main conduit when the head reachesa first chosen position along the path and to end such communicationwhen the head reaches a second chosen position, whereby in use eachcontainer in turn is able to be engaged by a respective head and flushedwith gas, wherein the heads are attached to a rotor which is mounted ona fixed shaft whereby the advancing containers are able to drive therotor and cause each head in turn to engage a respective container andeach container in turn to be engaged by a respective head.
 2. Apparatusas claimed in claim 1, wherein the rotor co-operates with acomplementary stationary member (`the stator`) to define the valvemeans, one of the stator and the rotor defining a circumferentialchamber in communication with an inlet for the flushing gas, and theother of the stator and the rotor defining a ring of outlet ports, eachin communication with a respective head, the arrangement being such thatrotation of the rotor brings each outlet port in turn into communicationwith the chamber and hence the inlet.
 3. Apparatus as claimed in claim2, wherein the chamber at any one time overlaps and hence communicateswith three or four gas ports.
 4. Apparatus as claimed in claim 2,wherein the contiguous faces of the stator and rotor are formed suchthat there is a narrow gap and hence gas layer therebetween. 5.Apparatus as claimed in claim 2, in which the heads are connected to therotor by means of flexible arms.
 6. Apparatus as claimed in claim 5,wherein there is a respective conduit separate from the arms whichconnects each head with a respective port in the said valve. 7.Apparatus as claimed in claim 2, wherein each head takes the form of acap having a slot in the rear side thereof.
 8. A method of flushing aline of advancing containers with gas comprising advancing amultiplicity of spaced apart gas supply heads in a vertical plane, eachengagable with a container, along an endless path such that each head inturn engages an advancing container and each advancing container in thesequence is engaged by a head, and supplying gas to each head when it isbetween chosen positions only, such positions including those in whichit is in engagement with a container, and thereby flushing thecontainers with gas, wherein the heads are attached to a rotor which ismounted on a fixed shaft whereby the advancing containers are able todrive the rotor and cause each head in turn to engage a respectivecontainer and each container in turn to be engaged by a respective head.9. A method as claimed in claim 8, wherein the containers are bottles.